Chest and Abdominal Muscles
All muscles of Chest and Abdominal Region with their Origin, Insertion, Nerve Supply and Action
Chest Muscles
(A) Pectoralis major:-
Origin – Anterior surface of medial two-third of the clavicle, Half the breadth of the anterior surface of manubrium and sternum up to the 6th costal cartilage of ribs, Second to sixth costal cartilages and Aponeurosis of the external oblique muscle of abdomen.
Insertion – Bilaminar tendon on the lateral lip of the bicipital groove.
Nerve Supply – Lateral and Medial Pectoral Nerves.
Action – Abduction, internal rotation, flexion and extension of shoulder arm.
(B) Pectoralis minor:-
Origin – 3, 4, 5 ribs near the costochondral junction.
Insertion – Upper surface and medial border of the coracoid process of scapula.
Nerve Supply – Lateral and Medial Pectoral Nerves.
Action – Forcefully inspiration and draw the scapula forward.
(C) Subclavius:-
Origin – First rib at the costochondral junction.
Insertion – Subclavian groove in the middle one-third of the clavicle.
Nerve Supply – Nerve to subclavius from the upper trunk of brachial plexus.
Action – Depression of clavicle and elevation of first rib.
(D) Serratus anterior:-
Origin – Eight digitations from the upper eight ribs in the midaxillary plane and from the fascia covering the intervening intercostal muscles.
Insertion – The first digitation is inserted from the superior angle to the root of the spine. The next two digitations are inserted lower down on the medial border and the lower five digitations are inserted into a large triangular area over the inferior angle.
Nerve Supply – The long thoracic nerve (C5 to C7).
Action – Forcefully inspiration and protraction and upward rotation of the Scapulothoracic joint.
Abdominal Muscles
(A) Rectus abdominis:-
Origin – Pubis symphysis, pubic crest.
Insertion – Xiphoid process, costal cartilages of ribs 5-7.
Nerve Supply – Subcostal Nerve (T12) and Intercostal Nerve (T7-T11).
Action – Expiration and Trunk flexion.
(B) External abdominal oblique:-
Origin – External surfaces of ribs 5-12.
Insertion – linea alba, pubic tubercle and anterior half of iliac crest.
Nerve Supply – Intercostal Nerve, Subcostal Nerve and Iliohypogastric Nerve.
Action – Trunk flexion and Expiration.
(C) Internal abdominal oblique:-
Origin – Anterior two-thirds of the iliac crest.
Insertion – Inferior border of ribs 10-12, linea alba and pubic crest.
Nerve Supply – Intercostal Nerve, Subcostal Nerve, iliohypogastric Nerve and ilioinguinal Nerve.
Action – Trunk rotation, flexion and Expiration.
(D) Transverse abdominis:-
Origin – Internal surface of costal cartilage of ribs 7-12 and iliac crest.
Insertion – Linea alba, pubic crest and pectinal line of pubic.
Nerve Supply – Intercostal Nerve (T7-T11) and subcostal Nerve (T12).
Action – Trunk rotation and Expiration.